Fuel dispensing nozzles are utilized to deliver fuel into the fuel tank of a vehicle through a fill opening in the tank. Such nozzles typically include a main body portion, a spout connected and carried by the main body portion for insertion into the fill opening of the fuel tank on the vehicle and a connector portion for connecting the nozzle onto the outer end of a hose which delivers fuel from the pump to the nozzle. The main body portion includes a fuel passageway therethrough and a main popper valve disposed within the passageway for controlling the dispensing of fuel through the nozzle.
One problem with use of such nozzles is that the poppet valve is opened manually by the operator pulling on a lever extending from the main body portion. When the lever is released, the main poppet valve returns to the closed position and fuel flow is stopped. Consequently, such fuel nozzles may be provided with a hold-open mechanism which is engaged to maintain fuel flow without requiring the operator to continue holding the valve open. Various approaches to such hold-open mechanisms have been suggested. For example U.S. Pat. No. 4,265,281 to Oberrecht discloses a trigger pivotally mounted on a fuel valve handle which selectively engages with a rack strip which is connected to the hand guard of the fuel dispensing nozzle. U.S. Pat. No. 4,572,255 to Rabinovich discloses a hold-open catch including notches pivotally attached to the rearward portion of the hand guard which selectively engages the outboard end portion of the fuel valve lever. U.S. Pat. No. 5,067,533 to Carder et al. discloses a hold-open mechanism with a clip pivotally attached to the hand guard which selectively engages a step on the fuel valve lever.
However, providing a hold-open mechanism such as those discussed above, while it overcomes the limitation of requiring the operator to continue to hold the fuel dispensing nozzle while pumping fuel, creates additional problems. It is readily understood that fuel is a very combustible liquid. Therefore, overfilling is to be avoided not only to avoid a loss of fuel but also to avoid creation of the serious safety problem associated with open puddles of combustible fuel near pumps in service stations.
This problem is addressed, in part, by inclusion of a shut-off mechanism. This safety feature prevents spillage of fuel onto the ground and contamination of both the air and the soil. Such shut-off mechanisms typically include a venturi within the main body portion of the nozzle which is connected to the outer end of the spout by an internal passageway within the spout. In use, the flow of fuel through the nozzle creates a partial vacuum in this shut-off passageway which draws air out of the fuel tank, which continues so long as fuel is being dispensed and the shut-off passageway remains open. However, when the outer end of this shut-off passageway is blocked by fuel within the vehicle fuel tank, the flow of air ceases and the venturi action creates a substantially increased vacuum. This increased vacuum releases the trigger and permits the closing of the main poppet valve to interrupt the flow of fuel through the nozzle into the vehicle fuel tank.
Such fuel level sensitive shut-off mechanisms only operate to prevent overflow if the fuel dispensing nozzle is kept in the gas tank during operation. Should the fuel nozzle be removed or fall out of the gas tank during operation, fuel flow may continue and the fuel level sensitive shut-off mechanism will fail to prevent the undesirable fuel flow. Such a situation can arise, for example, when a customer, either intentionally to avoid payment or inadvertently, drives away in the customer's automobile while fuel is still flowing. Consequently, there are certain situations where the owner of the service station may wish or be required by Government regulations to prevent use of the hold-open mechanism.
To prevent use of hold-open mechanisms such as those in the United States patents discussed above, some part of the hold-open mechanism itself must be removed. Various problems are present in such an approach. For example, flexibility is lost as removal of the parts may involve difficult and time consuming manual operations. In fact, depending upon the manufacturing method used, such designs may not even allow removal of parts to allow the hold-open mechanism to be disabled. This prevents an owner of the device from switching the nozzle frequently. For example, in some areas the risk of customers driving off while fuel is being dispensed to avoid making payment may be much higher during the nighttime hours. Consequently, it may be desirable to provide the customer with the benefit of the hold-open mechanism during daytime and disabling this feature at night but the difficulty of switching the nozzle on a daily basis is too burdensome.
Another problem with removing parts of the hold-open mechanism to disable it is that the parts being removed are relatively expensive. They are also small enough to be easily misplaced, thereby requiring additional such parts to be purchased if the owner should later desire to set up the nozzle with the hold-open mechanism enabled. In addition, as discussed in U.S. Pat. No. 4,265,281, where disabling the hold-open mechanism involves removal of part of the mechanism, dimensional issues are important to maintain the relative positioning of the two selectively engaging portions of the hold-open mechanism. Making such pieces removable increases the difficulty of maintaining the dimensional tolerances between numerous movable mechanical components of the fuel dispensing nozzle. In addition, should the removable rack in U.S. Pat. No. 4,265,281 be placed on a flat surface and come in contact with heavy objects, as is possible in a service station environment, the rack itself may be flattened and become ineffective as a hold-open device.
With the foregoing in mind, it is an object of the present invention to provide a fuel dispensing nozzle that overcomes the disadvantages and deficiencies of prior fuel dispensing nozzles.
A more specific object of the present invention is to provide a fuel dispensing nozzle that provides a flexible and inexpensive mechanism for switching a fuel dispensing nozzle from manual only to automatic hold-open operation.